1. Hold the line against the rod handle, then release it at the end of the forward cast, or execute a downward haul. Both of these will insure that there's no slack in the line and that the rod is fully loaded. 2. Make sure you begin the forward cast just before the fly stops moving and the D loop begins to collapase. 3. If you're casting a weight forward line, make sure at least the end of the belly is inside the rod tip. If it isn't, the running line isn't thick enough to transmit all the power of the cast. 4. Make sure you are using a loading move at the start of the forward cast. Begin the cast by keeping your wrist locked and rotating you're body forward - the angle of the rod shouldn't change - then execute your power snap.